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<a name="1" href="#1">1</a>   <em class="comment">/*</em>
<a name="2" href="#2">2</a>   <em class="comment"> * $Header$</em>
<a name="3" href="#3">3</a>   <em class="comment"> * $Revision: 1128 $</em>
<a name="4" href="#4">4</a>   <em class="comment"> * $Date: 2006-02-05 13:49:04 -0800 (Sun, 05 Feb 2006) $</em>
<a name="5" href="#5">5</a>   <em class="comment"> *</em>
<a name="6" href="#6">6</a>   <em class="comment"> * ====================================================================</em>
<a name="7" href="#7">7</a>   <em class="comment"> *</em>
<a name="8" href="#8">8</a>   <em class="comment"> * Copyright 2000-2002 bob mcwhirter &amp; James Strachan.</em>
<a name="9" href="#9">9</a>   <em class="comment"> * All rights reserved.</em>
<a name="10" href="#10">10</a>  <em class="comment"> *</em>
<a name="11" href="#11">11</a>  <em class="comment"> *</em>
<a name="12" href="#12">12</a>  <em class="comment"> * Redistribution and use in source and binary forms, with or without</em>
<a name="13" href="#13">13</a>  <em class="comment"> * modification, are permitted provided that the following conditions are</em>
<a name="14" href="#14">14</a>  <em class="comment"> * met:</em>
<a name="15" href="#15">15</a>  <em class="comment"> * </em>
<a name="16" href="#16">16</a>  <em class="comment"> *   * Redistributions of source code must retain the above copyright</em>
<a name="17" href="#17">17</a>  <em class="comment"> *     notice, this list of conditions and the following disclaimer.</em>
<a name="18" href="#18">18</a>  <em class="comment"> * </em>
<a name="19" href="#19">19</a>  <em class="comment"> *   * Redistributions in binary form must reproduce the above copyright</em>
<a name="20" href="#20">20</a>  <em class="comment"> *     notice, this list of conditions and the following disclaimer in the</em>
<a name="21" href="#21">21</a>  <em class="comment"> *     documentation and/or other materials provided with the distribution.</em>
<a name="22" href="#22">22</a>  <em class="comment"> * </em>
<a name="23" href="#23">23</a>  <em class="comment"> *   * Neither the name of the Jaxen Project nor the names of its</em>
<a name="24" href="#24">24</a>  <em class="comment"> *     contributors may be used to endorse or promote products derived </em>
<a name="25" href="#25">25</a>  <em class="comment"> *     from this software without specific prior written permission.</em>
<a name="26" href="#26">26</a>  <em class="comment"> * </em>
<a name="27" href="#27">27</a>  <em class="comment"> * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS</em>
<a name="28" href="#28">28</a>  <em class="comment"> * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED</em>
<a name="29" href="#29">29</a>  <em class="comment"> * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A</em>
<a name="30" href="#30">30</a>  <em class="comment"> * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER</em>
<a name="31" href="#31">31</a>  <em class="comment"> * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,</em>
<a name="32" href="#32">32</a>  <em class="comment"> * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,</em>
<a name="33" href="#33">33</a>  <em class="comment"> * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR</em>
<a name="34" href="#34">34</a>  <em class="comment"> * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF</em>
<a name="35" href="#35">35</a>  <em class="comment"> * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING</em>
<a name="36" href="#36">36</a>  <em class="comment"> * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS</em>
<a name="37" href="#37">37</a>  <em class="comment"> * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.</em>
<a name="38" href="#38">38</a>  <em class="comment"> *</em>
<a name="39" href="#39">39</a>  <em class="comment"> * ====================================================================</em>
<a name="40" href="#40">40</a>  <em class="comment"> * This software consists of voluntary contributions made by many</em>
<a name="41" href="#41">41</a>  <em class="comment"> * individuals on behalf of the Jaxen Project and was originally</em>
<a name="42" href="#42">42</a>  <em class="comment"> * created by bob mcwhirter &lt;bob@werken.com> and</em>
<a name="43" href="#43">43</a>  <em class="comment"> * James Strachan &lt;jstrachan@apache.org>.  For more information on the</em>
<a name="44" href="#44">44</a>  <em class="comment"> * Jaxen Project, please see &lt;<a href="http://www.jaxen.org/" target="alexandria_uri">http://www.jaxen.org/</a>>.</em>
<a name="45" href="#45">45</a>  <em class="comment"> *</em>
<a name="46" href="#46">46</a>  <em class="comment"> */</em>
<a name="47" href="#47">47</a>  <strong>package</strong> org.jaxen.function;
<a name="48" href="#48">48</a>  
<a name="49" href="#49">49</a>  <strong>import</strong> java.util.List;
<a name="50" href="#50">50</a>  
<a name="51" href="#51">51</a>  <strong>import</strong> org.jaxen.Context;
<a name="52" href="#52">52</a>  <strong>import</strong> org.jaxen.Function;
<a name="53" href="#53">53</a>  <strong>import</strong> org.jaxen.FunctionCallException;
<a name="54" href="#54">54</a>  <strong>import</strong> org.jaxen.Navigator;
<a name="55" href="#55">55</a>  <em>/**</em>
<a name="56" href="#56">56</a>  <em> * &lt;p></em>
<a name="57" href="#57">57</a>  <em> * &lt;b>4.2&lt;/b></em>
<a name="58" href="#58">58</a>  <em> * &lt;code>&lt;i>string&lt;/i> substring(&lt;i>string&lt;/i>,&lt;i>number&lt;/i>,&lt;i>number?&lt;/i>)&lt;/code></em>
<a name="59" href="#59">59</a>  <em> * &lt;/p></em>
<a name="60" href="#60">60</a>  <em> * </em>
<a name="61" href="#61">61</a>  <em> * &lt;blockquote src="<a href="http://www.w3.org/TR/xpath" target="alexandria_uri">http://www.w3.org/TR/xpath</a>"> </em>
<a name="62" href="#62">62</a>  <em> * &lt;p>The &lt;b>substring&lt;/b> function returns the</em>
<a name="63" href="#63">63</a>  <em> * substring of the first argument starting at the position specified in</em>
<a name="64" href="#64">64</a>  <em> * the second argument with length specified in the third argument. For</em>
<a name="65" href="#65">65</a>  <em> * example,</em>
<a name="66" href="#66">66</a>  <em> * </em>
<a name="67" href="#67">67</a>  <em> * &lt;code>substring("12345",2,3)&lt;/code> returns &lt;code>"234"&lt;/code>.</em>
<a name="68" href="#68">68</a>  <em> * If the third argument is not specified, it returns the substring</em>
<a name="69" href="#69">69</a>  <em> * starting at the position specified in the second argument and</em>
<a name="70" href="#70">70</a>  <em> * continuing to the end of the string. For example,</em>
<a name="71" href="#71">71</a>  <em> * &lt;code>substring("12345",2)&lt;/code> returns &lt;code>"2345"&lt;/code>.</em>
<a name="72" href="#72">72</a>  <em> * &lt;/p></em>
<a name="73" href="#73">73</a>  <em> * </em>
<a name="74" href="#74">74</a>  <em> * &lt;p></em>
<a name="75" href="#75">75</a>  <em> * More precisely, each character in the string (see &lt;a</em>
<a name="76" href="#76">76</a>  <em> * href="<a href="http://www.w3.org/TR/xpath" target="alexandria_uri">http://www.w3.org/TR/xpath</a>#strings">[&lt;b>3.6 Strings&lt;/b>]&lt;/a>) is considered to have a</em>
<a name="77" href="#77">77</a>  <em> * numeric position: the position of the first character is 1, the</em>
<a name="78" href="#78">78</a>  <em> * position of the second character is 2 and so on.</em>
<a name="79" href="#79">79</a>  <em> * &lt;/p></em>
<a name="80" href="#80">80</a>  <em> * </em>
<a name="81" href="#81">81</a>  <em> * &lt;blockquote> &lt;b>NOTE: &lt;/b>This differs from Java and ECMAScript, in</em>
<a name="82" href="#82">82</a>  <em> * which the &lt;code>String.substring&lt;/code> method treats the position</em>
<a name="83" href="#83">83</a>  <em> * of the first character as 0.&lt;/blockquote></em>
<a name="84" href="#84">84</a>  <em> * </em>
<a name="85" href="#85">85</a>  <em> * &lt;p></em>
<a name="86" href="#86">86</a>  <em> * The returned substring contains those characters for which the</em>
<a name="87" href="#87">87</a>  <em> * position of the character is greater than or equal to the rounded</em>
<a name="88" href="#88">88</a>  <em> * value of the second argument and, if the third argument is specified,</em>
<a name="89" href="#89">89</a>  <em> * less than the sum of the rounded value of the second argument and the</em>
<a name="90" href="#90">90</a>  <em> * rounded value of the third argument; the comparisons and addition</em>
<a name="91" href="#91">91</a>  <em> * used for the above follow the standard IEEE 754 rules; rounding is</em>
<a name="92" href="#92">92</a>  <em> * done as if by a call to the &lt;b>&lt;a href="#function-round">round&lt;/a>&lt;/b></em>
<a name="93" href="#93">93</a>  <em> * function. The following examples illustrate various unusual cases:</em>
<a name="94" href="#94">94</a>  <em> * &lt;/p></em>
<a name="95" href="#95">95</a>  <em> * </em>
<a name="96" href="#96">96</a>  <em> * &lt;ul></em>
<a name="97" href="#97">97</a>  <em> * </em>
<a name="98" href="#98">98</a>  <em> * &lt;li></em>
<a name="99" href="#99">99</a>  <em> * &lt;p></em>
<a name="100" href="#100">100</a> <em> * &lt;code>substring("12345", 1.5, 2.6)&lt;/code> returns</em>
<a name="101" href="#101">101</a> <em> * &lt;code>"234"&lt;/code></em>
<a name="102" href="#102">102</a> <em> * &lt;/p></em>
<a name="103" href="#103">103</a> <em> * &lt;/li></em>
<a name="104" href="#104">104</a> <em> * </em>
<a name="105" href="#105">105</a> <em> * &lt;li></em>
<a name="106" href="#106">106</a> <em> * &lt;p></em>
<a name="107" href="#107">107</a> <em> * &lt;code>substring("12345", 0, 3)&lt;/code> returns &lt;code>"12"&lt;/code></em>
<a name="108" href="#108">108</a> <em> * </em>
<a name="109" href="#109">109</a> <em> * &lt;/p></em>
<a name="110" href="#110">110</a> <em> * &lt;/li></em>
<a name="111" href="#111">111</a> <em> * </em>
<a name="112" href="#112">112</a> <em> * &lt;li></em>
<a name="113" href="#113">113</a> <em> * &lt;p></em>
<a name="114" href="#114">114</a> <em> * &lt;code>substring("12345", 0 div 0, 3)&lt;/code> returns &lt;code>""&lt;/code></em>
<a name="115" href="#115">115</a> <em> * &lt;/p></em>
<a name="116" href="#116">116</a> <em> * &lt;/li></em>
<a name="117" href="#117">117</a> <em> * </em>
<a name="118" href="#118">118</a> <em> * &lt;li></em>
<a name="119" href="#119">119</a> <em> * &lt;p>.</em>
<a name="120" href="#120">120</a> <em> * &lt;code>substring("12345", 1, 0 div 0)&lt;/code> returns</em>
<a name="121" href="#121">121</a> <em> * </em>
<a name="122" href="#122">122</a> <em> * &lt;code>""&lt;/code></em>
<a name="123" href="#123">123</a> <em> * &lt;/p></em>
<a name="124" href="#124">124</a> <em> * &lt;/li></em>
<a name="125" href="#125">125</a> <em> * </em>
<a name="126" href="#126">126</a> <em> * &lt;li></em>
<a name="127" href="#127">127</a> <em> * &lt;p></em>
<a name="128" href="#128">128</a> <em> * &lt;code>substring("12345", -42, 1 div 0)&lt;/code> returns</em>
<a name="129" href="#129">129</a> <em> * &lt;code>"12345"&lt;/code></em>
<a name="130" href="#130">130</a> <em> * &lt;/p></em>
<a name="131" href="#131">131</a> <em> * &lt;/li></em>
<a name="132" href="#132">132</a> <em> * </em>
<a name="133" href="#133">133</a> <em> * &lt;li></em>
<a name="134" href="#134">134</a> <em> * &lt;p></em>
<a name="135" href="#135">135</a> <em> * </em>
<a name="136" href="#136">136</a> <em> * &lt;code>substring("12345", -1 div 0, 1 div 0)&lt;/code> returns</em>
<a name="137" href="#137">137</a> <em> * &lt;code>""&lt;/code> &lt;/blockquote></em>
<a name="138" href="#138">138</a> <em> * </em>
<a name="139" href="#139">139</a> <em> * @author bob mcwhirter (bob @ werken.com)</em>
<a name="140" href="#140">140</a> <em> * </em>
<a name="141" href="#141">141</a> <em> * @see &lt;a href="<a href="http://www.w3.org/TR/xpath" target="alexandria_uri">http://www.w3.org/TR/xpath</a>#function-substring"</em>
<a name="142" href="#142">142</a> <em> *      target="_top">Section 4.2 of the XPath Specification&lt;/a></em>
<a name="143" href="#143">143</a> <em> */</em>
<a name="144" href="#144">144</a> <strong>public</strong> <strong>class</strong> <a href="../../../org/jaxen/function/SubstringFunction.html">SubstringFunction</a> implements <a href="../../../org/jaxen/Function.html">Function</a>
<a name="145" href="#145">145</a> {
<a name="146" href="#146">146</a> 
<a name="147" href="#147">147</a>     <em>/**</em>
<a name="148" href="#148">148</a> <em>     * Create a new &lt;code>SubstringFunction&lt;/code> object.</em>
<a name="149" href="#149">149</a> <em>     */</em>
<a name="150" href="#150">150</a>     <strong>public</strong> <a href="../../../org/jaxen/function/SubstringFunction.html">SubstringFunction</a>() {}
<a name="151" href="#151">151</a> 
<a name="152" href="#152">152</a>     
<a name="153" href="#153">153</a>     <em>/**</em><em> Returns a substring of an XPath string-value by character index.</em>
<a name="154" href="#154">154</a> <em>     *</em>
<a name="155" href="#155">155</a> <em>     * @param context the context at the point in the</em>
<a name="156" href="#156">156</a> <em>     *         expression when the function is called</em>
<a name="157" href="#157">157</a> <em>     * @param args a list that contains two or three items</em>
<a name="158" href="#158">158</a> <em>     * </em>
<a name="159" href="#159">159</a> <em>     * @return a &lt;code>String&lt;/code> containing the specifed character subsequence of </em>
<a name="160" href="#160">160</a> <em>     *     the original string or the string-value of the context node</em>
<a name="161" href="#161">161</a> <em>     * </em>
<a name="162" href="#162">162</a> <em>     * @throws FunctionCallException if &lt;code>args&lt;/code> has more than three</em>
<a name="163" href="#163">163</a> <em>     *     or less than two items</em>
<a name="164" href="#164">164</a> <em>     */</em>
<a name="165" href="#165">165</a>     <strong>public</strong> Object call(<a href="../../../org/jaxen/Context.html">Context</a> context,
<a name="166" href="#166">166</a>                        List args) throws FunctionCallException
<a name="167" href="#167">167</a>     {
<a name="168" href="#168">168</a>         <strong>final</strong> <strong>int</strong> argc = args.size();
<a name="169" href="#169">169</a>         <strong>if</strong> (argc &lt; 2 || argc > 3){
<a name="170" href="#170">170</a>             <strong>throw</strong> <strong>new</strong> <a href="../../../org/jaxen/FunctionCallException.html">FunctionCallException</a>( <span class="string">"substring() requires two or three arguments."</span> );
<a name="171" href="#171">171</a>         }
<a name="172" href="#172">172</a> 
<a name="173" href="#173">173</a>         <strong>final</strong> <a href="../../../org/jaxen/Navigator.html">Navigator</a> nav = context.getNavigator();
<a name="174" href="#174">174</a> 
<a name="175" href="#175">175</a>         <strong>final</strong> String str = StringFunction.evaluate(args.get(0), nav );
<a name="176" href="#176">176</a>         <em class="comment">// The spec doesn't really address this case</em>
<a name="177" href="#177">177</a>         <strong>if</strong> (str == <strong>null</strong>) {
<a name="178" href="#178">178</a>             <strong>return</strong> <span class="string">""</span>;
<a name="179" href="#179">179</a>         }
<a name="180" href="#180">180</a> 
<a name="181" href="#181">181</a>         <strong>final</strong> <strong>int</strong> stringLength = (StringLengthFunction.evaluate(args.get(0), nav )).<strong>int</strong>Value();
<a name="182" href="#182">182</a> 
<a name="183" href="#183">183</a>         <strong>if</strong> (stringLength == 0) {
<a name="184" href="#184">184</a>             <strong>return</strong> <span class="string">""</span>;
<a name="185" href="#185">185</a>         }
<a name="186" href="#186">186</a> 
<a name="187" href="#187">187</a>         Double d1 = NumberFunction.evaluate(args.get(1), nav);
<a name="188" href="#188">188</a> 
<a name="189" href="#189">189</a>         <strong>if</strong> (d1.isNaN()){
<a name="190" href="#190">190</a>             <strong>return</strong> <span class="string">""</span>;
<a name="191" href="#191">191</a>         }
<a name="192" href="#192">192</a>         <em class="comment">// Round the value and subtract 1 as Java strings are zero based</em>
<a name="193" href="#193">193</a>         <strong>int</strong> start = RoundFunction.evaluate(d1, nav).<strong>int</strong>Value() - 1;
<a name="194" href="#194">194</a> 
<a name="195" href="#195">195</a>         <strong>int</strong> substringLength = stringLength;
<a name="196" href="#196">196</a>         <strong>if</strong> (argc == 3){
<a name="197" href="#197">197</a>             Double d2 = NumberFunction.evaluate(args.get(2), nav);
<a name="198" href="#198">198</a> 
<a name="199" href="#199">199</a>             <strong>if</strong> (!d2.isNaN()){
<a name="200" href="#200">200</a>                 substringLength = RoundFunction.evaluate(d2, nav ).intValue();
<a name="201" href="#201">201</a>             }
<a name="202" href="#202">202</a>             <strong>else</strong> {
<a name="203" href="#203">203</a>                 substringLength = 0;
<a name="204" href="#204">204</a>             }
<a name="205" href="#205">205</a>         }
<a name="206" href="#206">206</a>         
<a name="207" href="#207">207</a>         <strong>if</strong> (substringLength &lt; 0) <strong>return</strong> <span class="string">""</span>;
<a name="208" href="#208">208</a> 
<a name="209" href="#209">209</a>         <strong>int</strong> end = start + substringLength;
<a name="210" href="#210">210</a>         <strong>if</strong> (argc == 2) end = stringLength;
<a name="211" href="#211">211</a>             
<a name="212" href="#212">212</a>         <em class="comment">// negative start is treated as 0</em>
<a name="213" href="#213">213</a>         <strong>if</strong> ( start &lt; 0){
<a name="214" href="#214">214</a>             start = 0;
<a name="215" href="#215">215</a>         }
<a name="216" href="#216">216</a>         <strong>else</strong> <strong>if</strong> (start > stringLength){
<a name="217" href="#217">217</a>             <strong>return</strong> <span class="string">""</span>;
<a name="218" href="#218">218</a>         }
<a name="219" href="#219">219</a> 
<a name="220" href="#220">220</a>         <strong>if</strong> (end > stringLength){
<a name="221" href="#221">221</a>             end = stringLength;
<a name="222" href="#222">222</a>         }
<a name="223" href="#223">223</a>         <strong>else</strong> <strong>if</strong> (end &lt; start) <strong>return</strong> <span class="string">""</span>;
<a name="224" href="#224">224</a>         
<a name="225" href="#225">225</a>         <strong>if</strong> (stringLength == str.length()) {
<a name="226" href="#226">226</a>             <em class="comment">// easy case; no surrogate pairs</em>
<a name="227" href="#227">227</a>             <strong>return</strong> str.substring(start, end);
<a name="228" href="#228">228</a>         }
<a name="229" href="#229">229</a>         <strong>else</strong> {
<a name="230" href="#230">230</a>             <strong>return</strong> unicodeSubstring(str, start, end);
<a name="231" href="#231">231</a>         }
<a name="232" href="#232">232</a>         
<a name="233" href="#233">233</a>     }
<a name="234" href="#234">234</a> 
<a name="235" href="#235">235</a>     <strong>private</strong> <strong>static</strong> String unicodeSubstring(String s, <strong>int</strong> start, <strong>int</strong> end) {
<a name="236" href="#236">236</a> 
<a name="237" href="#237">237</a>         StringBuffer result = <strong>new</strong> StringBuffer(s.length());
<a name="238" href="#238">238</a>         <strong>for</strong> (<strong>int</strong> jChar = 0, uChar=0; uChar &lt; end; jChar++, uChar++) {
<a name="239" href="#239">239</a>             <strong>char</strong> c = s.<strong>char</strong>At(jChar);
<a name="240" href="#240">240</a>             <strong>if</strong> (uChar >= start) result.append(c);
<a name="241" href="#241">241</a>             <strong>if</strong> (c >= 0xD800) { <em class="comment">// get the low surrogate</em>
<a name="242" href="#242">242</a>                 <em class="comment">// ???? we could check here that this is indeed a low surroagte</em>
<a name="243" href="#243">243</a>                 <em class="comment">// we could also catch StringIndexOutOfBoundsException</em>
<a name="244" href="#244">244</a>                 jChar++;
<a name="245" href="#245">245</a>                 <strong>if</strong> (uChar >= start) result.append(s.charAt(jChar));
<a name="246" href="#246">246</a>             }
<a name="247" href="#247">247</a>         }
<a name="248" href="#248">248</a>         <strong>return</strong> result.toString();
<a name="249" href="#249">249</a>     }
<a name="250" href="#250">250</a> }
</pre>
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